1. Field
The disclosed concept pertains generally to circuit breakers, switchgear compartments, and interlocks. In particular, the disclosed concept pertains to radio frequency identifier-actuated circuit breaker coding interlocks.
2. Background Information
Circuit breakers provide a means for controlling a supply of electrical power to a circuit. A trip unit, such as an electronic trip unit control module, is commonly used to interface with the breaker to control tripping characteristics, including the rate of tripping and the trip current. Trip units may be removable from the breaker for servicing and for replacement by trip units having alternate tripping characteristics.
Circuit interrupters, such as for example and without limitation, circuit breakers, are typically used to protect electrical circuitry and people in the vicinity of electrical circuitry from damage due to an overcurrent condition, such as an overload condition, a short circuit, or another fault condition, such as an arc fault or a ground fault. Circuit breakers typically include separable contacts. The separable contacts may be operated either manually by way of an operator handle or automatically in response to a detected fault condition. Typically, such circuit breakers include an operating mechanism, which is designed to rapidly open and close the separable contacts, and a trip mechanism, such as a trip unit, which senses multiple potential fault conditions to trip the breaker automatically. Upon sensing a fault condition, the trip unit trips the operating mechanism to a trip state, which moves the separable contacts to their open position.
Fault conditions in circuit breakers are generally detected either by sensing the current flowing through the protected circuit or by sensing the temperature of conductors in the circuit breaker. Circuit breakers generally employ a mechanism such as an electronic trip unit or a magnetic trip unit to initiate a trip operation based on the current flowing through the protected circuit. Trip operations initiated by an electronic trip unit or magnetic trip unit are usually either instantaneous or initiated after a predetermined delay.
The intent of using a breaker coding interlock system is safety. It is imperative for ratings such as voltage, continuous current, and number of cycles, that the breaker can be interlocked in such a way that a breaker of a lower rating may not be inserted into a switchgear compartment with a higher rating, but that a breaker of a higher rating may be inserted and used in a switchgear compartment with a lower rating in certain instances.
FIG. 1 is a front view showing a circuit breaker 10 and cell 12, in accordance with the prior art. The circuit breaker 10 includes wheels 13 and a plurality of breaker code pins 14 attached to a surface 15 of the circuit breaker 10 and protruding outwardly and downwardly therefrom. The cell 12 includes a plurality of cell code pins 16 attached to a surface 17 of the cell 12 and protruding outwardly and upwardly therefrom.
FIG. 2 is a partial side view of the circuit breaker 10 and the cell 12, as shown in FIG. 1. The arrow indicates that the circuit breaker 10 enters or passes into the cell 12. The cell code pins 16 and corresponding surface 17 are positioned on the bottom surface of the cell 12.
FIG. 3 is a partial side view of the circuit breaker 10 passed into the cell 12. The breaker code pins 14 are shown in alignment with the cell code pins 16.
FIG. 4 is a detailed view of the breaker code pins 14 and the cell code pins 16 shown in FIG. 1. FIG. 4 shows the breaker code pins 14 and the cell code pins 16 in an alignment such that the breaker codes pins 14 and the cell code pins 16 do not interfere with each other as the circuit breaker 10 is allowed to pass or enter into the cell 12.
FIG. 5 is also a detailed view of the breaker code pins 14 and the cell code pins 16 shown in FIG. 1. FIG. 5 shows the breaker code pins 14 and the cell code pins 16 in an alignment such that there is interference between these pins 14,16 when it is attempted to pass or enter the circuit breaker 10 into the cell 12. The circuit breaker 10 is precluded from entering the cell 12 beyond the code pins 14,16.
It is known to use a torsional interference pin system having ten locations with three levels of variation to account for the variations that require coding to implement the interlocking system shown in FIGS. 1-5. The three levels of variation can be coded as 0 for no pin, 1 for short pin and 2 for long pin.
Radio Frequency (RF) devices are quite popular in many applications such as Radio Frequency Identification (RFID) systems and remote sensing. For example, RFID systems consist of one or more radio frequency tags or transponders (RFID tags) and one or more radio frequency readers or interrogators (RFID readers). The RFID tags typically include an integrated circuit (IC) chip, such as a complementary metal oxide semiconductor (CMOS) chip, and an antenna connected thereto for allowing the RFID tag to communicate with an RFID reader over an air interface by way of RF signals. In a typical RFID system, one or more RFID readers query the RFID tags for information stored on them, which can be, for example, identification numbers, user written data, or sensed data. RFID systems have thus been applied in many application areas to track, monitor, and manage items as they move between physical locations.
Radio frequency identification (RFID) tags are used in a variety of applications, such as inventory control and security. Unlike barcode tracking systems, the advantage of these more intelligent RFID systems is that an RFID system can store specific information about an article and can read that information on a tag without being directly connected to the tag as well as without requiring line of sight or a particular orientation. This means that RFID systems can be largely automated, reducing the need for manual scanning
RFID tags are typically placed on, or in, articles or containers. The RFID tags work in conjunction with an RFID base station. The base station supplies an electromagnetic wave output, which acts as the carrier frequency. Data is then used to modulate the carrier frequency to transmit specific information. RFID systems typically operate at either a low frequency range (generally less than 100 MHz), or a higher frequency range (greater than 100 MHz). In many applications, one such higher frequency range is between 800 and 1000 MHz (defined as the UHF Band), with 915 MHz being the most common high frequency currently utilized in the United States. Most RFID systems utilize frequency hopping centered around this frequency, such that the overall frequency range is approximately 902 to 928 MHz. A second high frequency used by RFID tags in the United States is 2450 MHz.
Many RFID tags contain integrated circuits, which are capable of storing information. Depending on the specific implementation of the RFID tag, the integrated circuit may be capable of replacing stored information with new information at a later time. When the base station requests data, the integrated circuit supplies the information that it has stored in response to that request. In those RFID tags that permit information to be rewritten, the integrated circuit overwrites its existing information when new data is received from the base station.
In addition to the integrated circuit, the RFID tags contain an antenna. The antenna is needed to receive the electromagnetic waves generated by the base station, and to transmit data via the same frequency. The configuration of the antenna can vary, and includes flat coils, patches, micro-strip antennas, strip-line antennas and dipoles.
RFID tags may be self-powered and contain an internal power supply such as a battery. Other RFID tags are field-powered, meaning that radio frequency energy is received by the tag antenna as an AC signal and rectified to form a DC voltage that is used to power the integrated circuit.
Thus, it is an object of the disclosed concept to develop RFID-actuated coding interlocks for use in circuit breakers to assure that a circuit breaker having an unacceptable identity, e.g., voltage or current rating, is blocked from passing or entering a switchgear compartment.